KR101176170B1 - method for preventing overcurrent of Electronic Ballast for HID Lamp and Electronic Ballast for HID Lamp thereof - Google Patents

Abstract

The present invention provides a power supply unit for supplying a power supply voltage, a DC-DC converter having a switching element and outputting a current for turning on the high-pressure discharge lamp from the power supplied by the power supply unit in accordance with the switching element on and off; A ballast controller for adjusting a duty ratio to adjust the amount of voltage to be output from the DC converter, a pulse width modulation processor for outputting a pulse signal for controlling on / off of the switching element according to the duty ratio adjusted by the ballast controller; And an overcurrent prevention processor for controlling the input of the pulse signal to the switching element based on the duty ratio adjusted to prevent the overcurrent from the DC-DC converter. do.

According to the present invention, by preventing excessive current from flowing inside the ballast, the weak components of the ballast are not destroyed or the high-pressure discharge lamp emits light stronger than conventional light. In addition, even if the pulse width modulation module of the ballast does not operate normally, a certain level of current is continuously output therein, thereby ensuring the functional stability of the electronic ballast for high-pressure discharge lamps.

High-pressure discharge light, ballast, overcurrent, anti-, pulse width modulation, MOSFET

Description

Method for preventing overcurrent of electronic ballast for high-pressure discharge lamps and its electronic ballast for high-pressure discharge lamps {{method for preventing overcurrent of Electronic Ballast for HID Lamp and Electronic Ballast for HID Lamp}

1 is a graph showing a change in current with time in a conventional electronic ballast for a high-pressure discharge lamp.

Figure 2 is a block diagram of the electronic ballast for high pressure discharge lamp according to an embodiment of the present invention.

3 is a circuit diagram of an electronic ballast for a high-pressure discharge lamp according to an embodiment of the present invention.

Figure 4 is a graph showing the change of current with time in the electronic ballast for a high-pressure discharge lamp according to an embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

10: electronic ballast for high-pressure discharge lamp 100: ballast processing unit

110: power supply processing unit 120: DC-DC converter

121: switching element 130: back pressure circuit

140: high pressure igniter 150: DC-AC inverter

160: high-pressure discharge lamp 200: ballast control processing unit

210: current measurement processing unit 220: ballast controller

230: pulse width modulation processing unit 300: overcurrent prevention processing unit

The present invention relates to an electronic ballast for High Intensity Discharge (HID), and more particularly, for a high-pressure discharge lamp that prevents excessive current flow inside the ballast due to a malfunction of a pulse width modulation module. It relates to a method for preventing overcurrent of an electronic ballast and an electronic ballast for a high-pressure discharge lamp thereof.

Ballasts for high-pressure discharge lamps have a disadvantage that the ballast of the conventional passive element is bulky and heavy, and most of them are developed as an electronic ballast and mounted on a vehicle.

The electronic ballast is implemented to apply a plurality of components (high voltage discharge lamp, high voltage igniter, converter, inverter) by appropriately adjusting the power supply voltage of the vehicle by using a pulse width modulation module.

At this time, if the pulse width modulation module malfunctions, the power supply voltage of the vehicle is applied as it is to a plurality of components as it is not only a waste of power, but also a weak component (for example, MOSFET) is destroyed due to excessive current. have.

If a large amount of current is not applied to the electronic ballast without being regulated, there is a problem that the power supply in the vehicle is imbalanced, and thus, the possibility of starting off or a fire may increase during driving.

In addition, the electronic ballast causes the power of the vehicle to be directly applied to the high-pressure discharge lamp as the MOSFET (switching element) is destroyed to emit strong light.

This way, the driver on the other side suddenly sees a strong light while driving, narrowing the field of vision and may be at risk of an accident.

However, if the electronic ballast is implemented to detect the amount of current to immediately cut off the power supply to solve such a problem, the driver of the vehicle due to the sudden turn off of the high-pressure discharge lights, there is a problem that does not properly grasp the driving situation is dangerous.

Accordingly, there is a need for a technology that not only prevents excessive current from flowing in the electronic ballast, but also properly maintains the high-pressure discharge lamp so as not to emit strong light or suddenly turn off.

1 is an exemplary view of application of a conventional electronic ballast.

Referring to Figure 1, it can be seen a graph showing the change in the current (A) with time (ms) in the conventional electronic ballast.

At this time, the pulse width modulation module operates normally in the section from 0ms to 0.5ms in the graph, and the pulse width modulation control circuit malfunctioned in the section after 0.5ms.

Therefore, it can be seen that the current is periodically output from the battery supply power so that the current flowing in the ballast is constant in the interval from 0ms to 0.5ms.

In the section after 0.5 ms, it can be seen that the current is continuously output from the battery power supply due to the malfunction of the pulse width modulation control circuit.

As a result, the MOSFET (switching element) is destroyed in a certain period after 0.8 ms, and a large amount of current is continuously output, causing excessive current to flow inside the ballast.

As described above, in the conventional electronic ballast, when the pulse width modulation control circuit malfunctions and a large amount of current flows inside the ballast, it may endanger the driver and damage the driver of the opposite vehicle. There is no preparedness.

SUMMARY OF THE INVENTION The present invention has been made to solve such a conventional problem, and an object of the present invention is to provide an overcurrent preventing processing method of an electronic ballast for a high-pressure discharge lamp that prevents excessive current flow inside the ballast, and an electronic ballast for the high-pressure discharge lamp. .

According to an aspect of the present invention for achieving the above object, a power supply for supplying a power supply voltage, and a current for turning on the high-pressure discharge lamp from the power supplied by the power supply in accordance with the switching element on and off with a switching element DC-DC converter for outputting a, a ballast control unit for adjusting the duty ratio to adjust the amount of voltage to be output from the DC-DC converter, and controlling the on-off of the switching element according to the duty ratio adjusted by the ballast control unit And a pulse width modulation processing unit for outputting a pulse signal for controlling the current, and an overcurrent prevention processing unit controlling the input of the pulse signal to the switching element based on a duty ratio adjusted to prevent an overcurrent from the DC-DC converter. It provides an electronic ballast for a high-pressure discharge lamp, characterized in that.

Preferably, the DC-DC converter is a flyback type converter.

Preferably, the overcurrent prevention processing unit includes a capacitor and charges the capacitor by a pulse signal of the pulse width modulation processing unit to determine whether the duty ratio adjusted by the DC-DC converter is a duty ratio for outputting the overcurrent. It controls the input of the pulse signal to the switching element of the DC-DC converter depending on whether it is overcharged or not.

More preferably, the overcurrent prevention processing unit compares the capacitor that charges the charge with the pulse signal of the pulse width modulation processing unit with the voltage of the capacitor and a predetermined reference voltage, and the voltage is higher if the voltage of the capacitor is smaller than the predetermined reference voltage. A comparator for outputting a pulse signal of the capacitor and outputting a low voltage pulse signal if the voltage of the capacitor is not smaller than the preset reference voltage, and a high voltage pulse signal must be input from the comparator and the pulse width modulation processing unit to obtain a high voltage. And an AND gate for outputting a pulse signal.

According to another aspect of the present invention, a first step of adjusting the duty ratio for controlling the amount of the input power supply to turn on the high-pressure discharge lamp, and switching to adjust the amount of supply power is released in accordance with the adjusted duty ratio And a third step of outputting a pulse signal for controlling the device, and a third step of controlling the input of the pulse signal to the switching element based on the adjusted duty ratio. Provide a prevention treatment method.

Preferably, the third step includes charging the capacitor with a pulse signal, comparing the voltage of the charge charged in the capacitor with a predetermined reference voltage to determine whether the capacitor is overcharged, and the capacitor If it is determined that is overcharged so that the pulse signal output by the second step is not input to the switching element.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

2 is a block diagram of the electronic ballast 10 for a high-pressure discharge lamp according to an embodiment of the present invention.

2, the electronic ballast 10 for a high-pressure discharge lamp outputs a power supply voltage under the control of the switching element to control the ballast processing unit 100 and the switching element of the ballast processing unit 100 to turn on the high-pressure discharge lamp Ballast control processing unit 200 for adjusting the amount of current to be output, and overcurrent prevention processing unit 300 for preventing overcurrent is output from the ballast processing unit 100 due to the control of the ballast control processing unit 200 do.

First, the ballast processor 100 includes a power supply processor 110 for supplying a power voltage through a battery and a switching element 121 to switch and output the power voltage supplied from the power supply processor 110 in a high frequency fashion. Generating a igniter voltage for lighting a high-pressure discharge lamp from the DC-DC converter 120, a back voltage circuit 130 for back pressure-processing the power voltage output by the DC-DC converter 120, and a back voltage-processed power voltage. High-voltage igniter 140, a DC-AC inverter 150 for converting a DC power supply voltage output from the DC-DC converter 120 into an AC power supply voltage, and outputting the high-voltage igniter 140 and DC. And a high-pressure discharge lamp 160 that emits light due to the voltage input from the AC inverter 150.

The DC-DC converter 120 includes a switching element 121 to switch and output the power supply voltage on the primary side supplied by the power supply processing unit 110 to the secondary side in response to the switching on and off of the switching element 121. Perform the function.

The switching element 121 is turned on and off by an input pulse signal to control the amount of current to be output from the DC-DC converter 120.

At this time, the input pulse signal is output from the ballast control processing unit 200 to pass through the overcurrent prevention processing unit 300 to control the amount of current to be output from the DC-DC converter 120, and then to the switching element 121 It is entered.

In detail, the ballast control processing unit 200 outputs a pulse signal to control the amount of current to be output from the DC-DC converter 120, and the overcurrent protection processing unit 300 is a DC-DC converter ( In operation 120, whether the overcurrent is output is detected and the corresponding pulse signal is input to the switching element 121.

The back pressure circuit 130 performs a function of back pressure processing the power supply voltage output from the DC-DC converter 120.

The high voltage igniter 140 generates an igniter voltage, which is a high voltage for initially starting the high-pressure discharge lamp 160 from the back pressure-treated power supply voltage of the back pressure circuit 130 through mutual induction of the coils.

The DC-AC inverter 150 converts the DC power input from the DC-DC converter 120 into an AC power having a variable voltage and applies it to the high voltage discharge lamp 160.

The high voltage discharge lamp 160 is started due to the igniter voltage of the high voltage igniter 140 and is turned on due to the power applied from the DC-AC inverter 150.

In particular, the high-pressure discharge lamp 160 is one of a plurality of known high-pressure discharge lamps (mercury lamp, metal halide lamp, high pressure sodium lamp, pulse start lamp) according to one embodiment of the present invention Although implemented as a metal halide lamp, the present invention is not limited thereto.

At this time, when the high voltage igniter voltage is supplied to the metal halide lamp, the argon gas sealed in the discharge tube is destroyed so that the glow discharge, which is a long blue light, is maintained for about 0 to 5 seconds. The mercury atoms vaporize as the internal temperature of the discharge tube rises, so that the metal halite lamp transitions to an arc discharge and emits a visible wavelength.

On the other hand, the ballast control processing unit 200 monitors the amount of current output from the DC-DC converter 120 to output a pulse signal to control the switching element 121 to adjust the current to flow to the ballast processing unit 100 Do this.

In detail, the ballast control processor 200 includes a current sensor to measure the current output from the DC-DC converter 120.

The ballast control processing unit 200 adjusts the duty ratio based on a pulse width modulation (PWM) method, which is a known technique, based on the measured result, and based on the adjusted duty ratio, the switching element. A pulse signal to control 121 is output.

In this case, the pulse width modulation method is a technique of adjusting the duty ratio, which is a ratio of a predetermined time and a time for supplying power during the predetermined time so that an appropriate current flows in the circuit.

Therefore, the ballast control processor 200 adjusts the duty ratio and outputs a pulse signal to control the switching element 121 based on the adjusted duty ratio. As a result, the amount of current output from the DC-DC converter 120 is proportional to the duty ratio.

The overcurrent prevention processing unit 300 serves to prevent the overcurrent from being output from the DC-DC converter 120 of the ballast processing unit 100 due to the voltage output by the ballast control processing unit 200.

To this end, the overcurrent prevention processing unit 300 receives a pulse signal from the ballast control processing unit 200 and determines whether the duty ratio is a duty ratio for outputting the overcurrent in the DC-DC converter 120 to convert the corresponding pulse signal into a switching element. Enter or do not enter

3 is a circuit diagram of the electronic ballast for a high-pressure discharge lamp shown in FIG.

The ballast processing unit 100 is a power supply processing unit 110, a DC-DC converter 120, a back voltage circuit 130, to turn on the high-pressure discharge lamp 160 provided with the power supply voltage supplied through the battery, The high voltage igniter 140, the DC-AC inverter 150, and the high pressure discharge lamp 160 are configured to be included.

The DC-DC converter 120 includes a switching element M5 to switch and output a power supply voltage according to on / off of the switching element M5.

In particular, the DC-DC converter 120 has a switching element M5 and a primary coil and a secondary coil outputting a power supply voltage in response to on / off of the switching element M5 according to an embodiment of the present invention. Although it is implemented to include a flyback converter (L1) wound to, but the present invention is not limited thereto.

In the flyback converter L1, when the switching element M5 is turned on, the current is charged in the primary coil, and when the switching element M5 is turned off, the current of the primary coil is transferred to the secondary coil.

Therefore, the switching element M5 is turned on and off by a pulse signal input from the ballast control processing unit 200 through the overcurrent prevention processing unit 300 to adjust the amount of current output from the flyback converter L1. .

At this time, the switching element M5 is implemented as a MOSFET mainly used in the output terminal of the power circuit based on a known technique, but the present invention is not limited thereto.

The back pressure circuit 130 performs a back pressure process on the power supply voltage output by the DC-DC converter 120.

In particular, the back voltage circuit 130 includes two diodes D1 and D2 and two capacitors C1 and C2 to double the voltage input from the DC-DC converter 120 according to one embodiment of the present invention. Although it is implemented to boost, the present invention is not limited thereto.

The high voltage igniter 140 generates an instantaneous voltage igniter voltage through mutual induction of the coil from the power supply voltage back-pressured by the back pressure circuit 130, and applies the generated igniter voltage to the high voltage discharge lamp 160. .

The DC-AC inverter 150 converts the DC power input from the DC-DC converter 120 into an AC power having a variable voltage and outputs the same.

In particular, the DC-AC inverter 150 is implemented as a full bridge inverter composed of four transistors M1, M2, M3, and M5 according to an embodiment of the present invention, but the present invention is limited thereto. It is not.

The high-pressure discharge lamp 160 starts to light due to the igniter voltage applied from the high-voltage igniter 140 and receives the AC power from the DC-AC inverter 150 to maintain light emission.

Meanwhile, the ballast control processor 200 includes a current measurement processor 210, a ballast controller 220, and a pulse width modulation processor 230 to monitor and control the amount of current to be output from the DC-DC converter 120. It is configured by.

The current measurement processor 210 performs a function of outputting a voltage proportional to the current to the ballast controller 220 so that the current output from the DC-DC converter 120 can be measured.

The ballast controller 220 adjusts the duty ratio so that the amount of current to be output from the DC-DC converter 120 is controlled based on the voltage input from the current measurement processor 210.

The pulse width modulation processor 230 outputs a pulse signal based on the duty ratio adjusted by the ballast controller 220.

The output pulse signal adjusts the on / off of the switching element 121, thereby controlling the amount of current flowing in the ballast processing unit 100 by controlling the time that the current is output from the DC-DC converter.

On the other hand, the overcurrent prevention processing unit 300 controls the input of the pulse signal to the switching element M5 in order to prevent the overcurrent from being output from the DC-DC converter 120 due to the corresponding pulse signal.

To this end, the overcurrent prevention processing unit 300 is a capacitor (C6) for charging the charge due to the pulse signal, a comparator (U2A) for detecting whether the capacitor (C6) is overcharged, and the pulse signal is input to the switching element (M5) And an AND gate U1 for controlling the control.

When the capacitor C6 receives a pulse signal, the capacitor C6 charges and discharges the power voltage supplied from the power supply processor 110 with the charge resistor R7 and the discharge resistor R5.

The comparator U2A receives the voltage of the capacitor C6 through the − terminal and compares the preset reference voltage through the + terminal.

In other words, the comparator U2A outputs a pulse signal of a high voltage (about 5 V) at the output terminal if the voltage at the negative terminal is lower than the reference voltage at the positive terminal, and if the voltage at the negative terminal is not lower than the reference voltage at the positive terminal. A pulse signal of low voltage (about 0V) is output.

That is, when the voltage charged in the capacitor C6 becomes overcharged and becomes larger than the reference voltage, the comparator U2A detects this and outputs a pulse signal having a low voltage (about 0V).

The AND gate U1 outputs a high voltage (about 5V) pulse signal to the switching element M5 when all of the high voltage (about 5V) pulse signals are input from the comparator U2A and the pulse width modulation processing unit 230. do.

On the contrary, if any of the comparator U2A and the pulse width modulation processing unit 230 does not output a high voltage (about 5 V) pulse signal, the AND gate U1 does not output a high voltage (about 5 V) pulse signal. .

In summary, when the voltage is not overcharged due to the pulse signal of the ballast control processing unit 200 in the capacitor C6, the comparator U2A outputs a pulse signal of a high voltage (about 5V) so that the AND gate U1 switches. A pulse signal of a high voltage (about 5 V) is input to the element M5.

Therefore, the switching element M5 is turned on by the pulse signal of the high voltage (about 5V), so that the current is output from the DC-DC converter 110.

In addition, when the voltage is overcharged due to the pulse signal of the ballast control processing unit 200 in the capacitor C6, the comparator U2A outputs a pulse signal of a low voltage (about 0V) so that the AND gate U1 may switch to the switching element ( Input a low voltage pulse signal (about 0V) to M5).

Thus, the switching element M5 is turned off by the low voltage (about 0V) pulse signal so that the current is not output from the DC-DC converter 110. The capacitor C6 is discharged by the pulse signal of the low voltage (about 0V) of the AND gate 200.

Then, the capacitor C6 recharges the voltage by the pulse signal again and then repeatedly discharges the battery. Thus, the overcurrent prevention processor 300 performs the switching element (B) by a cycle according to the overcharge and discharge of the capacitor C6. The pulse signal of the high voltage (5V) is input to M5).

4 is a graph showing a change in the current A with time (ms) in the electronic ballast according to an embodiment of the present invention.

Referring to FIG. 4, the ballast control processor 200 normally operates in a section of 0 ms to 0.5 ms in the graph, and the ballast control processor 200 malfunctions in a section after 0.5 ms.

In the period from 0 ms to 0.5 ms, the switching element M5 is turned on and off based on the duty ratio according to the normal operation of the ballast control processing unit 200 so that the DC-DC converter 120 outputs a current at a constant cycle. Can be.

At this time, the overcurrent prevention processing unit 300 receives a pulse signal from the ballast control processing unit 200 to charge and discharge the charge in the capacitor (C6). However, in the capacitor C6, since the ballast control processing unit 200 operates normally and outputs a pulse signal according to the duty ratio, it is not overcharged.

Therefore, the overcurrent prevention processor 300 inputs the same pulse signal as the pulse signal output from the ballast control processor 200 to the switching element M5.

It can be seen that the current continues to be output from the DC-DC converter 120 due to a malfunction of the ballast control processing unit 200 in a section from 0.5 ms to 1.0 ms.

At this time, the overcurrent prevention processing unit 300 is continuously input a pulse signal of a high voltage (about 5V) from the malfunctioning ballast control processing unit 200 to overcharge the capacitor (C6).

Accordingly, the overcurrent prevention processing unit 300 prevents the pulse signal of the ballast control processing unit 200 from being input to the switching element M5, thereby limiting the current output from the DC-DC converter 120 and discharging the capacitor C6. Let's do it.

Accordingly, it can be seen that the amount of current output from the DC-DC converter 120 dropped sharply at 1.0 ms.

Then, the discharged capacitor C6 recharges the charge by the pulse signal of the high voltage (about 5V).

Therefore, the overcurrent prevention processing unit 200 causes the same pulse signal output from the ballast control processing unit 200 to be input to the switching element M5 until the capacitor C6 is overcharged, and the capacitor C6 is overcharged. The pulse signal of the ballast control processing unit 200 is not inputted to the switching element M5 and the process of discharging the capacitor C6 is repeated.

Accordingly, the pulse signal of the high voltage (5V) is input to the switching element M5 due to the period of overcharging and discharging of the capacitor C6 in the section after 1.0, so that the DC-DC converter 120 supplies current at a constant period. You can see the output.

According to the present invention, the electronic ballast detects that the amount of current flowing inside the ballast is excessively increased due to a malfunction of the pulse width modulation module, thereby limiting the amount of output current, thereby destroying a weak component due to excessive current. It is possible to effectively prevent the high-pressure discharge lamp from emitting light stronger than the set light.

In addition, even if the pulse width modulation module does not normally regulate the amount of current output inside the ballast, the overcurrent prevention processing unit continuously flows a certain level of current inside the ballast by using a cycle according to the process of overcharging and discharging the capacitor. It guarantees the functional stability of the electronic ballast for high-pressure discharge lamps.

Claims (6)

A power supply for supplying a power voltage; A DC-DC converter having a switching element and outputting a current for turning on the high-pressure discharge lamp from the power supplied by the power supply unit in response to the switching on and off; A ballast controller for adjusting a duty ratio to adjust an amount of a voltage to be output from the DC-DC converter; A pulse width modulation processor for outputting a pulse signal for controlling on / off of the switching element according to the duty ratio adjusted by the ballast controller; And an overcurrent prevention processor for controlling the input of the pulse signal to the switching element based on the adjusted duty ratio to prevent overcurrent from the DC-DC converter. The overcurrent prevention processing unit After the capacitor is charged by the pulse signal of the pulse width modulation processing unit to determine whether the adjusted duty ratio is a duty ratio that can output the overcurrent in the DC-DC converter, the capacitor is overcharged The electronic ballast for a high-pressure discharge lamp, characterized in that for controlling the input of the pulse signal to the switching element of the DC-DC converter. The method of claim 1, wherein the DC-DC converter Electronic ballast for high-pressure discharge lamp, characterized in that the flyback type converter. delete The method of claim 1, wherein the overcurrent prevention processing unit A capacitor for charging electric charges by a pulse signal of the pulse width modulation processor; By comparing the voltage of the capacitor with a predetermined reference voltage, if the voltage of the capacitor is less than the predetermined reference voltage and outputs a pulse signal of a high voltage, if the voltage of the capacitor is not less than the predetermined reference voltage of a lower voltage A comparator for outputting a pulse signal, And an AND gate for outputting a high voltage pulse signal to the switching element when both a high voltage pulse signal is inputted from the comparator and the pulse width modulation processing unit. A first step of adjusting a duty ratio for controlling the amount of supply power input to turn on the high-pressure discharge lamp, A second step of outputting a pulse signal for controlling a switching element that adjusts an amount of the supply power emitted according to the adjusted duty ratio; A third step of controlling the input of the pulse signal to the switching element based on the adjusted duty ratio, The third step is Charging a capacitor by the pulse signal; Comparing the voltage of the charge charged in the capacitor with a predetermined reference voltage to determine whether the capacitor is overcharged; And if it is determined that the capacitor is overcharged, preventing the pulse signal output by the second step from being input to the switching element. delete

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